Nauplius ORIGINAL ARTICLE THE JOURNAL OF THE Decapod abundance and species richness BRAZILIAN CRUSTACEAN SOCIETY in the bycatch of Xiphopenaeus kroyeri (Heller, 1862) fishery, Santa Catarina, e-ISSN 2358-2936 www.scielo.br/nau southern Brazil www.crustacea.org.br Gilson Stanski orcid.org/0000-0002-4778-7336 Geslaine R. L. Goncalves orcid.org/0000-0001-7443-6913 Raphael C. Grabowski orcid.org/0000-0001-9414-8310 Milena R. Wolf orcid.org/0000-0003-1022-1360 Antonio Leão Castilho orcid.org/0000-0003-0001-9054 1 NEBECC – Group of Studies of Crustacean Biology, Ecology and Culture, Zoology Department, Institute of Biosciences of Botucatu, São Paulo State University (UNESP). Botucatu, São Paulo, Brazil. ZOOBANK: http://zoobank.org/urn:lsid:zoobank.org:pub:66F3A568-D904-49FE- BD91-7F8CAA31617F ABSTRACT We aimed to analyze the crustacean bycatch from the Xiphopenaeus kroyeri fishery in the Santa Catarina State and compare the bycatch’s biomass to that of the target species. Shrimp and environmental factors were sampled monthly from July 2010 through June 2011. For each crustacean species, we calculated the number of individuals, the relative abundance and the occurrence frequency. The relative abundance was classified as very abundant (Va), abundant (Ab) or low abundance (La), while the occurrence frequency was labeled continuous (Co), accessory (Ac) or accidental (Ad). We observed a total richness of 28 species, which is considered high for a subtropical region. Brachyura was the most frequent taxon (74%) followed by Penaeiodea (18%). Five species were considered Va (Arenaeus cribrarius, Callinectes danae, C. ornatus, Isochelis sawayai and Pleoticus muelleri), and eight species were considered Co (A. cribrarius, C. danae, C. ornatus, Farfantepenaeus paulensis, Hepatus pudibundus, Libinia spinosa, Litopenaeus schmitti and Sicyonia dorsalis), suggesting that the studied environment is heterogeneous and provides a variety of microhabitats, enabling many species to coexist. Therefore, the high species richness observed demonstrates the ecological importance CORRESPONDING AUTHOR of this region and thus the necessity of strategies aiming to minimize the Gilson Stanski [email protected] impacts caused by trawling fisheries. SUBMITTED 23 October 2018 ACCEPTED 18 March 2019 KEYWORDS PUBLISHED 23 May 2019 Babitonga Bay, fisheries impact, biodiversity, trawling, crustacean bycatch DOI 10.1590/2358-2936e2019007 All content of the journal, except where identified, is licensed under a Creative Commons attribution-type BY. Nauplius, 27: e2019007 1 Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com Stanski et al. Bycatch from the Xiphopenaeus kroyeri Fishery INTRODUCTION southern and southeastern Brazilian coast (Franco et al., 2009). Fishing activities generate food, income and jobs Furthermore, in order to understand the reasons for and are important for coastal communities (Bail and the presence or absence of a diversity of organisms in a Branco, 2007). However, overfishing has reduced given area, it is necessary to study and comprehend their profitable shrimp stocks (D’Incaoet al., 2002), affecting interactions with the environment and its resources. the target species and several others (bycatch) (Pezzuto Among the environmental components influencing the et al., 2006). occurrence and distribution of marine benthic species, Large amounts of bycatch are captured because of the sediment granularity and organic matter content the methods used to capture shrimp (i.e., trawling). and bottom water salinity and temperature exert great This fishing gear exhibits low selectivity (Souzaet al., influence on decapod crustaceans (Bertiniet al., 2004; 2017). In this procedure, non-profitable and small (or Mantelattoet al., 2004; Fantucci et al., 2009). juvenile) specimens are discarded back into the sea, Therefore, the aim of this study was to describe the usually dead. The discarded taxa are quite diverse, species richness and abundance of decapod crustaceans including fishes, crustaceans, mollusks, echinoderms comprising the bycatch from the X. kroyeri fishery, the and cnidarians (Coelho et al., 1986). influence of environmental factors on the bycatch, and Such a lack of selectivity in this fishing activity the monthly proportion of the target species biomass may lead to the reduction or even extinction of the local biodiversity. Compromising of key species might in relation to the bycatch biomass near Babitonga Bay. lead to biological instability in the ecosystem and a This bay is located on the northern coast of the state of decrease in the subsistence of hundreds of fishermen Santa Catarina, the area has a rich fauna in crustaceans, whose prosperity depends on this activity (Murray fishes, birds and aquatic mammals (Rodrigueset al., et al., 1992). 1998). The seabob shrimpXiphopenaeus kroyeri (Heller, 1862) fisheries in coastal areas catch a high diversity MATERIALS AND METHODS of bycatch causing considerable damage to the environment (Coelho et al., 1986), as observed in Decapods and environmental factors were sampled studies on the bycatch fauna of K. kroyeri in other monthly from July 2010 through June 2011 in five regions of Brazil. For example, Rodrigues-Filho et sampling stations parallel to the coast with depths al. (2016) have evaluated the seasonal cycles of the of 5, 8, 11, 14 and 17m. All sampling stations were carcinofauna caught in seabob shrimp fishing in previously established using the Global Positioning northeastern Brazil, Costa and Di Beneditto (2009) System (GPS), in the area adjacent to Babitonga Bay. and Costa et al. (2016) have studied on the northern Babitonga Bay is located in the northern littoral zone coast of Rio de Janeiro. Graça-Lopes et al. (1993a) off Santa Catarina State (geographical coordinates: have analyzed the composition and distribution of 26º02’00” ‒26º28’00”S and 48º28’00”‒48º50’00”W), decapod crustaceans associated with K. kroyeri fishery Brazil near the cities of Joinville, Itapoá and São in São Paulo state, and Graça-Lopes et al. (2002a) and Francisco do Sul (Fig. 1). Severino-Rodrigues et al. (2002) in Perequê Beach, Biological samples were collected using trawls with São Paulo State. All these studies have reported an sampling effort of 1h (speed: 2 knots) over a total area expressive richness of the bycatch in relation to the of 37,000m2 using a shrimp fishing boat equipped with target species. double-rig nets. After each trawl, nets were brought to Therefore, it is essential to create management the fishery boat, and the animals were sorted, identified plans that consider the marine biological community and placed in thermal boxes containing crushed ice. as a whole. This is fundamental for implementing The samples were then taken to the laboratory, where mitigating measures or evaluating the measures that we identified them down to species level according to already exist. Currently, the major mitigating measure Costa et al. (2003) and Melo (1996, 1999a) and we is a fisheries closure period, in which trawling activities quantified and weighed (g) each species (Grabowski are prohibited from March 1 through May 31 in the et al., 2014). Nauplius, 27: 2019007 2 Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com Stanski et al. Bycatch from the Xiphopenaeus kroyeri Fishery Figure 1. Studied region. The adjacent area from the Babitonga Bay, northern litoral of the Santa Catarina State, highlighting the sampled depths (source: Grabowski et al., 2014). Environmental factors 24h and then sieved through a sequence of six sieves. As a result, sediment was classified in the following We used a Van Dorn bottle to obtain bottom water granulometric classes: gravel (> 2mm), very coarse samples in each sampling station, and we measured its sand (1–2mm), coarse sand (0.5–1mm), medium temperature and salinity using a mercury thermometer sand (0.25–0.5mm), fine sand (0.125–0.25mm) and (to the nearest 0.1°C) and an optical refractometer (to very fine sand (0.0625–0.125mm). the nearest 0.1 psu), respectively. The grain size was then expressed on the phi scale Sediment samples were collected quarterly, (Φ), which corresponds to the measurement of the specifically once in each season e.g.( , summer: January central tendency for sediment samples (Suguio, 1973). to March). The methodology adopted in the subsequent The most frequently found granulometric fraction in analysis was based on previous studies (Håkanson and the sediment sample was determined by cumulative Jansson, 1988; Tucker, 1988). curves using the formula: M= Φ + Φ + Φ . The The sediment was obtained using a Peterson grab 16 50 84/3 phi classes were converted into granulometric fractions at each of the five sampling stations and frozen until using log , resulting in the following: -1 = Φ < 0 (gravel), laboratory analysis. In the laboratory, samples were 2 0 = Φ < 1 (coarse sand), 1 = Φ < 2 (medium sand), 2 dried in an oven at 70°C for 72h. Subsequently, 10g = Φ < 3 (fine sand), 3 = Φ < 4 (very fine sand) and Φ subsamples were placed in porcelain containers and ≥ 4 (silt + clay). weighed before drying in a muffle furnace at 500°C for 3h in order to burn off all the organic matter content. Bycatch analysis Subsequently, samples were weighed again, and the difference between the initial and final weights was For each crustacean species, we calculated the total considered the amount of organic matter associated number of individuals and the seasonal abundance. with the substrate. The relative abundance (RA) of each species was Other 100g subsamples were treated for 10 min in calculated as the number of that species divided by 250ml of a 0.2 N solution of NaOH in distilled water the total number of captured individuals (excluding to ease the separation of silt and clay from larger grains. the target species, X. kroyeri) (Costa et al., 2016). Next, subsamples were rinsed through a 0.0625mm The Catch Per Unit Effort (CPUE) was used to sieve in order to eliminate silt and clay. After that study, express the number of individuals captured in each subsamples were again dried in an oven at 60°C for hour of trawling (ind.